Barracuda Legend Kit Problems

[jladre]

"Beep...beep..beeep" sound?
Be sure that your coil cable has a good and not loose connection, the screen must properly connected to the ground, and last be sure your coil is properly fix to the shell so that it will not have movement inside during sweeping.

[raygdunn]

no i mean i cannot physically move it around if i move it BEEPBEEPBEEP i do not understand why? what wire are you using between the coil and board? I have a dual core foil covered + sheilded cable.

I'm with you now. I've yet to use coil screening. I'd do experience some mild ground effects on the PI-1 with a low capacitance thick plastic insulation wound coil, which is to be expected. Also I do remember the odd beep at end of a swing, until I tightened the coil restraints.

I use spare TV extension leads that come with video recorders and the like. Length a metre and a bit. (Just discovered that lengths do vary). Remove socket on one end only. I repurposed parts from a TV aerial splitter socket box for a plug to go in the wall of the electronics box. Plan B there would be to glue in the plug just cut off as they are a mating pair. That is of course the "use what's to hand" approach.

Ahh... I've pulled all the wires, added a battery and my Barracuda has had its first trip to the garden and yes random...ish Beep...Beep. I'm moving the coil around holding it mid lead, as there may be some hand capacitance effects, if I hold the bare coil. (Seems to make little difference actually). My first shot at sorting this will be securing the short coil ends leading to the cable. I'm using quite thick coil wire. I'll have to play with it later, but I mine would have to be coil movement I would have thought. Another idea will be trying it mobile with the PI-1. It may just be the same. Then try some another coil. Look for a pattern.

Stopping movement is one of the reasons for "potting" the coil. I've just got a few thread ties holding mine plus occasional masking tape securing it to a backing plastic disk for rigidity.

I'm very much with you now😞

Ray

[6666]

guys, i ask you to help me to ask bluetube to give clear pics of his board.

http://www.geotech1.com/forums/showthread.php?22993-Anchor-Baracuda-help

my english is bad... you know it, emotionally pale, so i hope on your assistance in that. write in his thread more and make a noise you can do.
if we will get the pics so i will see something new and tell you more.

Done.

[Impulse]

impulse were these taken with the old or new board?

This was the old board

[kt315]

Thanks Ray for these great pics.

guys, i ask you to help me to ask bluetube to give clear pics of his board.

http://www.geotech1.com/forums/showthread.php?22993-Anchor-Baracuda-help

my english is bad... you know it, emotionally pale, so i hope on your assistance in that. write in his thread more and make a noise you can do.
if we will get the pics so i will see something new and tell you more.

[Old cart]

I've already added a 10K pot. I had a "spider" wound coil (has former with 37 slots inside and out), which was very slow, as in insufficient delay adjustment. With the meter on it, the reading glitched, when I touched a certain area. I can only imagine it to be a scratched insulation short. I'll rewind.


I do have that interference. :-) It is annoying. I switched off my florescent "CSI style" magnifier/work light before taking the shots. 60Hz mains from the high voltage transformer, I'd guess.


Several photos from assorted angles, not 100% indentifiable but close I hope.

[ATTACH]35402[/ATTACH]
[ATTACH]35398[/ATTACH]
[ATTACH]35399[/ATTACH]
[ATTACH]35400[/ATTACH]
[ATTACH]35401[/ATTACH]

Ray

Thanks Ray for these great pics.

[Old cart]

Old cart it is polerized i will try it and see what happens.

To Clarify put the whichever pin the red lead is on, if the reading is positive , is where you should solder the cap + lead. I would interchange the red and black leads on the pins if the reading is negative to avoid any confusion about which pin is more positive.

[Old cart]

ok i have resurrected the old board and it has the same issue with a different coil? 11.4v batt volts. i will go back to the board that we have been working on and desolder the 330ohm balance resistor then take 5534 pin 3 and 6

here
[ATTACH]35392[/ATTACH]
[ATTACH]35393[/ATTACH]

impulse were these taken with the old or new board?

[Old cart]

5534 pin6 [ATTACH]35412[/ATTACH]

try adjusting you offset. The trace marker for ch1 should align
With the flat part of the waveform.

[Old cart]

Maybe something like this

http://www.parts-express.com/visaton-k50wp-16-2-full-range-water-resistant-speaker-16-ohm--292-540

These are Chinese, you should be able to get them in UK.

Impulse you might try disconnecting the buzzer. Maybe it is causing interference. Then repeat the pin 2-4 test.

[Old cart]

Hey guys sorry I haven't replied for a while my laptop has died (blue screen off death) I am using my phone for now so I cannot use my oscope till its fixed I am going to shorten the lead it is just over 1m it is a dual core shielded cable with a foil wrap should I swap it for coax?

on second thought this dual core coax probably has high capacitance. Swap it for coax as soon as you can.

[Old cart]

All 5? or the last one?

also the delay trim has a slight affect in terms of amplitude not relative time or position

and by calibrator signal you mean the scope signal?

here [ATTACH]35377[/ATTACH]

you should run scope cal, one of the traces is not the right amplitude.

[Old cart]

Ray for big metal these things need to be feet away to not be affected. Many PI's are so sensitive to metal and electrical interference that they can no be accurately tested indoors. I try to keep my coils at least three feet away from everything when testing. I also find that slight changes in the location of the coil can make a big difference. Beak in mind that at least here in the US floors are often constructed with nails or rebar. Both are iron and PI's are VERY sensitive to iron.

Let us know how your 40106 change out experience goes. Are you using real 40106s or Chinese knock offs?

There are several things that could cause crosstalk:

1. Defective chips
2. Flux on board
3. Capacitive coupling due to poor trace routing.
4. Inductive coupling due to poor trace or wiring routing.
5. Power supply bypassing due to inadequate decoupling caps on the board

Figuring which one or ones is causing the problems is sometime tough. You just have to attack them one at a time.
Replacing chips is easy as is cleaning the board.
Power supply bypassing is easy to check you just look for low noise on the individual supply pins. This can hard to do, particularly using cheap scopes and probes which are often noisy.

The coupling ones are perhaps the hardest to find and resolve. Sometimes reroute get wiring can help , sometimes the board must be relaid out.
It does appear the KT315 has this sorted.

[Impulse]

no i mean i cannot physically move it around if i move it BEEPBEEPBEEP i do not understand why? what wire are you using between the coil and board? i have a dual core foil covered + sheilded cable.

[raygdunn]

I thought i was the only ONE! Do you have the movement issue?

Hi Impulse,

If you refer to adjusting the Delay on the sampling pulse, that work fine for me. (I have the extra 10K pot to play with, but that just makes fine tuning easier)

I am finding real problems getting my coil far enough away from metal and other interference. It causes that rising decay slope to move to the right (so delay needs adjusting). It disappears completely off the 'scope scale, when an inch from desk metal. Never seen that before. It appears to be purely coil orientation rather than wires from PCB. Hmm remind me the PI-1 was detecting the metal log fireplace three feet away. Perhaps it was there and I didn't monitor it.

Ray